Cinematographic-printer light control



. @O O G OO O OO O OO O OO @OO O O 1 O 4 O Q O O J. A. BALL Filed August lO.

CINEMATOGHAPHIC PRINTER LIGHT CONTROL @@QDQQDDQDDQDIQDQQ Jan. 4, 1927 i 1J 13 1617 #9161.9 z

Patented Jan. 4, 1927.

UNITED STATES vPATENT OFFICE.

JOSEPH A.. BALL, OF CAMBRIDGE, MASSAGHUSETT ASSIGNOR TO TECHNICOLOR MO- TION PICTURE CORPORATION, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MAINE.

Application 'led August 10, 1923.

This invention relates to the production of cinematographic films and'particularly to an improvement in the method and apparatus for printing such films disclosed in 5 copending application Ser. No. 512,399, filed November 2, 1921.

In the production of the various Asections of a film negative from which the positive is produced, the average d-ensity of the negatives frequently varies due to variations in light conditions, speed of camera, or the like. It is of course desirable that in the positive the average illumination, particulai-ly for corresponding scenes, remainsY substantially constant. Also it is particularly desirable and necessary in the production of coinplcmental positives for the projection of color pictures that the color balance be properly maintained.

The present invention relates particularly to an automatic control to regulate theindividual exposure of the complementary positives in colored film production Without substantially changing the average exposure,

and the automatic variations of the printing illumination to maintain the effect in the positive substantially constant when printing through negative of different densities in either black-andwhite or color positive film production. '4

Prior to the present invention attempts have been made to control the printing illumination through the formation of a notch or indentation in the edge of the negative for operating a control mechanism having a' r-oller bearing against the edge of the film in a manner to engage the notch or indentation and to be actuated thereby. However this type of mechanism results in a constraint of the film which is objectionable in certain types of printers, as for example the apparatus described in the aforesaid application Where the film is positioned at the printing aperture by register pins and strained in the'vicinity ofthe aperture so that the pins may be free to do their positioning to a high degree of accuracy. It 1s prinit is quite important that the film be uncon- CINEMATOGRAPHIC-PRINTER LIGT CONTROL.

serial No. 656,658.

cipally for this reason that the older type of automatic light lcontrol is not satisfactory in this typev of machine and the present described invention hasl been evolved to overcome the difficulty.

An object of the invention is the provision of an improved method of controlling the printing illumination according to the density of the negative or joined negative sections from which the complete positive is to be produced, together with the provision of novel apparatus which may be satisfactorily employed to carry out such method. further object of the invention is the provision of an improved method and apparatus, employing the iilm negative itself asv a control for the illumination, which Will be positive and accurate in operation and which will not interfere with the accurate registration of the positive and negative films relating to each other at the printing Window or Windows. More specifically the object of the invention is the provision of an automatic light change control mechanism which .may be placed close to the printing aperture land yet which involves substantially'no constraint onA the film at the aperture.

Y, The invention may be utilized by laterally notching or indenting the negative film,

passing the film between yielding lateral guides engaging opposite edges of the film with an equal pressure, and varying the density of the printing illumination upon relativemovement of the guides occasioned by differences in Width of the film. The method further contemplates guiding the -film adjacent the point of edge engagement,

to prevent any transverse fiexion or buckling of the film. By this method unequal pressure against one side of the film is eliminated, derangement of the position of the film is prevented, and the illumination is satisfactorily varied according to difierences in width of the film. This mak-es it possible to form the control indentations either entirely at one side of the film or partially at each side of the film, the latter I a 'control circuit and are positionet to enof the arms.

gage each other and complete the circuit when a portion of iihnof' reduced width passes between the film engaging members on the arms. These arms are preferably floating or loosely pivoted freely to followA the edges of the film, swinging fromvside to side as an entirety but also being capable of relative movement as described. Ordinarily the arms hang i-n a vertical position, and, to relieve the film of pressure from the weight of the outwardly deflected ends of the arms with their film contacts, weights are preferably disposed at the opposite ends This provides a balanced gage device spanning the film, and responsive to very slight force to swing it from side to side so that it will guide or follow the film without disturbing the general movement and position of the film.

In order to illustrate the nature of the invention, one concrete embodiment has been shown in the accompanying drawings, in which z- Fig. l is viewof the automatic control mechanism Fig. 2 is af semi-diagrammatic view of the control circuit and the illumination control mechanism operated thereby;

Fig. 3 is a section on the line 3-3 of Fig. 1;

Fig. 4 is a section on the line 4-4 of Fig. 3;

Fig. 5 is a section on the line 5-5 of Fig. 1; and

Fig. 6 is a section on the line .6 6 of Fig. 5.

In the drawings, the reference character 10 denotes the frame portion of cinematographic film printing apparatus which supports a film guide plate 11 and second guide section 12. The section 12 is hinged at 13 to permit upward swinging for reception of' the film negative 14 and is locked in closed position .by latch 15. The lmvguides 11 and 12 have the proximate portions 16 and 17 fo'r engagement with the edges ofv the film and the recessed portions 18 and l19 spanning the central coated section of the film.

In operation the negative to be printed is suitably advanced through the film guide. In order that the printed luminosity may film 14 are provided with notches or indentation as at 20.

The present improved control members are designed to cooperate with these indentations or reduced portions of the film. They comprise a pair of sinuous arms 21 and 22 pivotally mounted upon pivot screw 23 on frame member 10. They have at one end the outwardly extending portions 24 and 25 bea-ring rollers 2G disposed in alignment with the spaces between members 16 and 1T to engage the edges of the film. Spring 2T yieldingly urges the arms inwardly to hold rollers 26 in engagement with the edges of the film. Contacts 28 on thc arms intermediate the pivotand rollers form part of control circuit 29 which is closed by cngage- The contacts 28 may be formed of platinum wire and set in insulated bushings 31 in arms 21 and 22.'

The mechanism for controlling the pri-nting illumination is similar to that shown in copending application previously referred to and comprises variable, resistances 33 and 34 connected through the source of current 32 to lights U and V iat the respective windows of the duplex printer. Taps from the resistance coils 33 and 34 are connected.

with vertical bars 35 which have a series of openings 36 to receive the contact plugs 37. A contact bar 38 slides in vertical guides 39 in juxtaposition to the bars 35 so as to contact with the plugs on the bars in any selected position. The circuit for the lamps is as follows: From one side of the source of current through conductor 40, thence through resistance 33, thence through one of the bars 35 to a plug 37 contacting with bar 38, thence through bar 38 to a plug 37 connecting with oneof the taps of resistance 34, thence in parallel through the resistance 34 and lambs U and V back to the source of current through conductor 41. The bar 38 is arranged to be stepped downwardly by means of escapement mechanism controlled by magnet 43 forming part of control circuit 29. In the left-hand bank the plugs are arranged according to the total amount of illumination desired while in the righthand bank the plugs are arranged to control Y the relative illumination of lights U and V. Control circuit 29 is completed through contacts 28 when rollers 26 strike reduced portions 20 of film 11 and momentarily actuates magnet 43 to shift the escapement 42 and loo" IUT

` gaged.

From the foregoing description the operation and advantages of the present improved' control mechanism will be evident and it will be seen that by virtue of the film passing between face engaging guides 16 and 17 it is held against transverse flexure while the balanced edge engaging members apply equal light pressure to both edges of the fini, freely following any variations in position of the film caused by other parts of the mechanism and relatively yielding according to variations iii width of the` film, completing the illumination control circuit to vary the illuiniiiation when 4engaging fiini portions of reduced width. l

I claim:

l. The combination with means vprovidingl a variable printing illumination for a cinematographic film, of a. control therefor in-' cluding intermediately pivoted counterweighted arms and means actuating the arms yieldingly to engage the edges of the. film.

2. The combination with means providing a variable printing illumination for a cinematographic film, of a control therefor including a support, a pivot thereon, a pair of v'counterweighted arms floating on the pivot and having film engaging portions, and ineans actuating said portions toward each other -'laterally to engage and follow thev contour of the edges of a film.

3. Apparatus for printing cinematographic film, including a variable source of luminosity, and control means therefor including mutually cooperating counterweighted spaced contact arms having portions yieldingly receiving the film therebetween.,

4. Apparatus for printingcinematographic film, including a variable source of -luminosity, and control means therefor including counterweighted spaced contact arms having portions yieldinglyv receiving the film therebetween and means for resiliently pressing the arms togtlier to effect a contact therebetween.

Apparatus for printing cineinatolgraphic film, including a variable source of luminosity, control means therefor including spaced contact arms having portions yieldingly receiving the film therebetween, contacts carried by the arms, Vand means for counter-balancing the arms to relieve the film of excess lateral pressure.

6. In apparatus for printing cinematograpliic film, the combination with an illumination varying mechanism, of a controlV therefor including counterbalanced floating arms' having portions for lateral engagement with the film, circuit closing members on the arms held in spaced relation by engagement of the arms with a standard width film, and

7. The combination with means for producing a variableillumination for printing cinematographic films, of, an electro-magneticv control therefor, a control circuit including the magnet and' a pairof contacts, supports for the contacts having film engaging portions holding the contacts apart when engaging a standard width ylilmygravity actuated means for 4balancing said supports and means urging the contacts together to close the control circuit when a film of reduced width passes between the engaging portions.

8. In cinematographic film printing mechanism, the combination. lwith a film guide of a pivot carried thereby, a pair of arms mounted on the the arms, gravity actuated means for balancing said arms, means for urging the contacts toward each other, and means on the arms for laterally engaging a film therebetween, the position and arrangement of the said means and the contacts being such that a normal width film willn hold the contacts in slightly spaced relation, whereby the contacts will interengage when a narrow film portion passes between the film engaging means on the arms. i

9. A einematograpliic film printing mechanism, including a source of printing lumiiiosity, relatively movable floating counterbalanced means adapted to engage opposite edges of a film with an equal pressure, and

means actuated by relative movement of edges of tli'e film and being movable together or relatively.

1l. The combination with guide means engaging opposite faces of a film member, of illumination controlling means engaging oppositeedges thereof, said face and edge engaging portions eoncomitantly engaging the same film section, and the illumination means comprising opposed edge contactors applying equal and balanced pressure to the edges of the film, said contactors being supported for joint swinging movement and for relative shifting movement.

pivot, contacts carried by lll! 12. The combination with means for guidv ing a film in a Apredetermined path, of crossed arms pivoted to the guide, said arms each having film engaging portions and eooperating electrical contacts disposed at one side of the pivot, and balancing means. on 'the arms at the opposite side of the pivot.

13. In 4cinematographic film printing mechanism, the combination With a ilm guide having portions holding the ilm against transverse eXure, of counterbalanced illumination control members laterally engaging the edges of the filme cooperating make and break contacts carried by said members and operable by variations in the film Width, and a control circuit including the contacts for varying the printing illumination as the control cireuit'is completed by engagement of the contacts.

Signed by me at Boston, Massachusetts, this 3rd day of August 1923.

JOSEPH A. BALL. 

